1. Field of the invention
This invention relates generally to miniature, blade terminal fuses currently used in motor vehicle electrical systems and described in U.S. Pat. No. 3,909,767 granted to H. L. Williamson et al and more particularly to a light indicating capability for identifying a blown, open circuit condition of such fuses.
2. Description of the prior art
Recent models of motor vehicles have electrical systems equipped with fuse panels which utilize miniature parallel blade terminal fuses, replacing the familiar cartridge type panels and fuses. These blade terminal fuses, a representative construction of which is described in said Williamson et al patent, provide two methods for identifying a blown, open circuit condition without removal of the fuse from the panel, namely, by a test instrument which may be applied to two test points accessible through openings in the top exposed surface of the fuse housing, or by visual inspection of the fuse-wire through the transparent housing. The requirement of a test instrument, per se, is a considerable disadvantage. Other disadvantages include the difficulty in making visual and test instrument inspection due to the often limited accessibility of the panel and fuses and the failure of visual inspection even after removal of the fuse from the panel when the failure of the fuse is due to a substantially invisible hair-line open circuit resulting from a slight circuit overload.
There is, therefore, a present need for providing such miniature, blade terminal fuses with a visible indicator of a blown, open circuit condition of the fuse which will make the blown fuse readily distinguishable from the other operating fuses in a fuse block.